JPS6349540Y2 - - Google Patents

Description

[Detailed description of the invention] This invention connects a gas flow path that supplies a mixed gas of air and gas fuel from a mixer and an oil flow path that supplies oil fuel to the cylinder head. Additionally, a flow rate regulating valve is provided in the gas flow path, an engine exhaust gas driven supercharger is connected to the air supply path to the mixer, and a flow path opening/closing valve is provided in the gas fuel supply path to the mixer. A pressure regulating valve is provided at a position downstream of the valve and the flow path, and the diaphragm for operating the pressure regulating valve is moved to the pressure increasing side by a spring and pilot air from the air supply path, and It is provided to be operated to the pressure reducing side by the gas pressure after pressure adjustment, and there is a gas operation mode in which the on-off valve is opened and the operation is performed mainly on gas fuel, and a gas operation mode where the on-off valve is closed and the operation is performed on oil fuel. The present invention relates to a dual fuel engine configured to be switched between an oil operating mode and an oil operating mode by a command signal.

In such an engine, in the gas operation mode, the air pressure supplied by the engine exhaust gas-driven supercharger fluctuates such that it becomes higher at high engine loads when a large amount of mixed gas is consumed;
In addition, even if the gas pressure supplied to the mixer fluctuates, the gas pressure is adjusted to maintain the differential pressure between the gas pressure supplied to the mixer and the air pressure within an appropriate range. However, if the engine load fluctuation range is wide, the differential pressure will deviate significantly from the desired range, and when the engine load is low,
This not only wastes gas fuel, but also causes the problem that the engine speed varies greatly from the desired speed when switching from the oil operation mode to the gas operation mode.

More specifically, the differential pressure between the gas pressure and the air pressure is determined by the urging force of the spring that urges the diaphragm, and the urging force increases as the engine load increases and the air pressure increases. The more the pressure is shifted toward the pressure increase side, the smaller it becomes. In order to prevent the output from decreasing due to insufficient gas pressure during high loads, the biasing force of the spring is set to maintain an appropriate differential pressure during high loads. This creates an inconvenience of excessive gas pressure and wasteful consumption of gas fuel, and if switching from oil operation mode to gas operation mode is performed under low load conditions, the engine speed will fluctuate greatly from the desired speed. There was an inconvenience. In addition, such an engine is equipped with a control unit that automatically opens and closes a flow rate regulating valve to maintain the engine speed within a set range, thereby suppressing fluctuations in the engine speed. Even in that case, fluctuations in engine speed could not be suppressed.

An object of the present invention is to make it possible to maintain differential pressure within an appropriate range regardless of engine load fluctuations by adding a simple structure.

The characteristic configuration of the dual fuel engine according to the present invention is as follows:
A two-stage operated valve mechanism for reducing the pilot air pressure supplied to the diaphragm is connected to the pilot flow passage for pilot air flow, and is adapted to the engine load so as to reduce the pilot air pressure only when the engine load is below the set load. The present invention is further provided with a control device that automatically operates the valve mechanism based on the above.

Next, the effects of the feature configuration of the present invention will be described.

That is, when the engine load is high, the valve mechanism is maintained in a high pressure supply state and the pressure regulating valve is operated as specified by the diaphragm, and when the engine load is low, the valve mechanism is maintained in a reduced pressure supply state. The pressure regulating valve is operated in a predetermined manner by the diaphragm in a state in which the diaphragm is switched to prevent unnecessary high pressure from being supplied to the diaphragm. In other words, if the biasing force of the diaphragm biasing spring is set to be within the appropriate range at high loads, the force will be higher than necessary at low loads, but this is offset by reducing the pilot air pressure. .

Therefore, even when the load is low in gas operation mode, the differential pressure between the gas pressure and air pressure to the mixer is maintained within an appropriate range to prevent excessive gas pressure, thereby reducing waste of gas fuel. Not only can consumption be suppressed, but it is also possible to prevent the engine speed from deviating significantly from the desired speed when switching from oil operation mode to gas operation mode. This also led to the creation of an excellent dual-fuel engine.

Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in Figure 1, a gas passage GR supplies a mixture of gas fuel such as city gas and air to multiple cylinder heads 2 of an engine 1, and oil fuel such as light oil or heavy oil is supplied to the cylinder heads 2 of the engine 1. oil flow path
A mixer 4, which can freely change the amount of mixed gas supplied by opening and closing a throttle valve 3 serving as a gas amount adjustment valve, is connected to the end of the gas flow path GR. A supply path r ₁ that supplies air from an engine exhaust gas-driven supercharger 5 and a gas fuel supply path r ₂ are connected to the mixer 4, respectively, and the gas fuel supply path r ₂ is connected to an electromagnetically operated A flow path opening/closing valve 6 and a pressure regulating valve 7 located on the downstream side of the flow channel are respectively provided, and an oil regulating valve for changing the amount of oil fuel supplied from the feed pump 8 to the injection nozzle 9. A variable injection amount pump 10 is connected in communication with the end of the oil flow path OR, and the air from the supercharger 5 bypasses the mixer 4 to supply auxiliary air to the gas flow path GR. A supply path _r3 is provided, and electromagnetically operated air valves 11 are provided to open and close the supply path _r3 , respectively.
The dual fuel engine is configured to be switchable between a gas operation mode in which the engine is operated mainly using gas fuel while supplying a small amount of oil fuel as pilot oil for ignition, and an oil operation mode in which oil fuel is used.

That is, in the gas operation mode, the on-off valve 6 is opened, the air valve 11 is held close to fully closed, and the variable pump 10 is fixed in a state where it injects a set amount, and in this state, the throttle valve 3 is The opening degree will be changed, and in the oil operation mode, the on-off valve 6 will be closed and the air valve 11 will be closed.
is held close to fully closed, and the throttle valve 3 is further operated to the set opening degree for air supply, and in this state, the injection amount of the variable pump 10 is changed.

The engine 1 includes an air conditioning compressor 1
2, and the throttle valve 3 and the variable pump 10 are automatically operated so as to maintain the engine speed within a set range regardless of fluctuations in the driving load of the compressor 12, that is, the engine load. First control unit for gas operation to be operated
S ₁ and an oil operation control section S ₂ are provided, respectively.
However, the first control section _S1 stores information for operating the throttle valve 3 to the set opening degree in the oil operation mode, and the second control section _S2
In the gas operation mode, the variable pump 10
Information for operating the fuel to inject a set amount is stored.

As shown in Figure 2, the operating mode is switched to oil operating mode during a certain period of time after engine startup or under abnormal conditions such as when gas fuel supply is insufficient, and to gas operating mode during normal conditions. The mode is configured to be automatically executed based on a command signal from the operation mode selection circuit 13 into which information from the start/stop operation circuit 13A and the trouble detection device 13B is input.

The mixer 4 includes a gas fuel supply path r ₂
The valve 4A that changes the opening degree of the outlet and the degree of communication between the air supply path _r1 and the gas flow path GR is connected to the spring 14.
It is provided so that it is operated to the closing side by the biasing force of and the mixed gas pressure supplied into the pressure chamber U through the vent hole 15, and to be operated to the opening side by the supplied air pressure. , the outlet opening degree and the communication opening degree are changed as the throttle valve 3 is opened and closed to supply mixed gas in a predetermined mixed state.

More specifically, for example, the throttle valve 3
When the valve is operated toward the closing side, the mixed gas pressure at the upstream side of the throttle valve 3 increases, and accordingly, the valve 4A moves toward the closing side to obtain a predetermined balance pressure state. Tutle valve 3
When the valve is operated toward the opening side, the mixed gas pressure at the upstream side of the throttle valve 3 becomes lower, and accordingly, the valve 4A moves toward the opening side so as to obtain a predetermined balance pressure state, and as a result, the mixture The structure is such that gas can be supplied in a predetermined mixed state regardless of fluctuations in the supply amount. In addition, in the oil operation mode, the valve 4A is opened by air pressure, and air passes through three throttle valves and enters the gas flow path.
At the same time as it flows into the GR, it flows into the gas supply path _r2 to suppress deformation damage to the diaphragm 16, which will be described later.

The pressure regulating valve 7 is operated so as to maintain the differential pressure between the gas pressure supplied to the mixer 4 and the air pressure within a certain range, that is, to maintain the gas pressure at a pressure higher than the air pressure by a set value. Therefore, the diaphragm 16 that automatically operates the pressure regulating valve 7 will be explained below.

That is, an L-shaped lever 17 for operating the pressure regulating valve 7 is provided so as to be swingable by the diaphragm 16, and a spring 18 is provided to bias the diaphragm 16 toward the pressure increasing side. A pilot flow path _r4 for pilot air flow for operation to the pressure increasing side is connected in communication with the air supply path _r1 , and a diaphragm 16 is also connected to the air supply path r1.
A passage 19 is provided for supplying gas after pressure adjustment to the diaphragm 16 to reduce the pressure. In other words, the gas pressure is adjusted to be higher than the air pressure by a pressure determined by the biasing force of the spring 18.

Pilot flow path _r4 for the flow of the pilot air
A two-stage operated electromagnetic on-off valve 20 is connected to the engine to release part of the pilot air into the atmosphere to reduce the pilot air pressure, and the supply pressure from the supercharger 5 is set as the engine load decreases. A pressure switch 21 is provided which is turned on when the pressure falls below a certain value. The operation mode selection circuit 1 is configured to operate the operation AND circuit 22 for the on-off valve 20 to open the on-off valve 20 only in the gas operation mode and when the engine load is less than or equal to the set load.
3, and a control device that is connected to the pressure switch 21 and automatically operates the on-off valve 20 so as to reduce the pilot air pressure only when the engine load is below the set load.

In short, the diaphragm biasing force spring 18
By setting the biasing force so as to maintain an appropriate differential pressure even when the engine load is high, it is possible to maintain an appropriate differential pressure even when the engine load is low.

Figure 3 A and B indicate 25% of the maximum load on engine 1.
These are experimental results showing the fluctuations in the engine speed due to switching from the oil operation mode to the gas operation mode when the on-off valve 20 is opened and closed, respectively, with a load applied. In the case of closing (see Figure 3 B), the engine speed increases by as much as 14% of the rated speed (1500 rpm), and it takes 10.2 seconds for the engine speed to settle down to the rated speed. However, when opening the on-off valve 20 (see Figure 3 A), the engine speed increases by only 6% of the rated speed at the maximum, and moreover, the engine speed settles to the rated speed. It was confirmed that it only takes 6.0 seconds to complete. However, in the illustrated graph, the vertical axis represents the rotation speed (Vrpm), and the horizontal axis represents time (T seconds).
It represents.

Although not shown as an example, when a large load was applied to the engine 1, the on-off valve 20 was opened and closed, and an experiment was conducted to determine the change in engine speed due to switching from oil operation mode to gas operation mode. It was confirmed that opening the on-off valve 20 caused a larger variation in the rotational speed.

Next, another example will be described.

In FIG. 4, an electromagnetically operated flow path switching valve 24 is provided to switch between a state in which air from the supercharger 5 is supplied to the diaphragm 16 through a pressure reducing valve 23 and a state in which air is supplied directly to the diaphragm 16 by bypassing the pressure reducing valve 23. A valve mechanism for reducing the pilot air pressure is configured, and an AND circuit 25 for operating the switching valve 24 is connected to each of the pressure switch 21 and the operation mode selection circuit 13, and This constitutes a control device.

In carrying out the present invention, the specific configuration of the valve mechanism for reducing the pilot air pressure is as described in the above embodiment.
In addition to providing an on-off valve 20, a pressure reducing valve 23, and a flow path switching valve 24, various modifications are possible.

In addition, as described in the embodiment, the valve mechanism operation control device is configured so that the valve mechanism 20 or 23, 24 can be switched to the pressure reducing state only in the gas operation mode, and in addition, in the oil operation mode, There is no particular problem in practical use even if the structure is configured so that the pressure can be switched to the pressure decreasing state. In addition to detecting engine load, air pressure is also detected.
Various changes can be made, such as detecting the opening degree of the throttle valve 3 or detecting the pressure of engine exhaust gas.

In addition, the engine 1 of the present invention can be used to drive various devices in addition to air conditioners, and the gas fuel used can be city gas as well as various types of combustible exhaust gas from sewage treatment systems and various factories. can be used.

[Brief explanation of the drawing]

The drawings show an embodiment of the dual fuel engine according to the present invention, FIG. 1 is a schematic sectional view, FIG. 2 is a block diagram showing the operation control configuration, and FIGS. 3A and 3B show experimental data. Furthermore, FIG. 4 is a schematic diagram of another embodiment. 2... Cylinder head, 3... Flow rate adjustment valve, 4
...Mixer, 6...Flow path opening/closing valve, 7...Pressure regulating valve, 16...Diaphragm, 18...Spring, 20 or 23, 24...Valve mechanism, GR...Gas flow path, OR... Oil flow path, r ₁ ... air supply path,
r ₂ ... Gas fuel supply path, r ₄ ... Pilot flow path.

Claims (1)

[Scope of utility model registration request] A gas flow path that supplies a mixed gas of air and gas fuel from the mixer 4 to the cylinder head 2.
GR and an oil flow path OR for supplying oil fuel are connected in communication, and a flow rate regulating valve 3 is provided in the gas flow path GR, and an air supply path to the mixer 4 is provided.
An engine exhaust gas-driven supercharger 5 is connected to r ₁ , and a gas fuel supply path r ₂ to the mixer 4 is connected to
A flow path opening/closing valve 6 and a pressure regulating valve 7 are provided on the downstream side of the flow channel, respectively, and the pressure regulating valve 7 is
the operating diaphragm 16, the spring 18,
The valve is provided so as to be operated to the pressure increasing side by the pilot air from the air supply path _r1 and to the pressure reducing side by the gas pressure after pressure adjustment, and the on-off valve 6 is opened to supply gas fuel. The dual-fuel engine is configured to be switched by a command signal between a gas operation mode in which the engine is mainly operated and an oil operation mode in which the on-off valve 6 is closed and the operation is performed using oil fuel. A two-stage operated valve mechanism 20 or 23, 24 that reduces the pilot air pressure supplied to the pilot air is connected to the pilot air flow path _r4 , and the pilot air pressure is reduced only when the engine load is less than the set load. , the valve mechanism 20 is adjusted based on the engine load.
or a dual fuel engine equipped with a control device to automatically operate 23 and 24.